Calavan was a sniper in Alpha Company under the command of Captain Buckler. He took part in the Battle of London. During the last part of the skirmish between Alpha Company and the Chimera a Widowmaker appears. Captain Buckler draws the Widowmaker's attention and tells Calavan to tag it. Calavan was presumably killed by the Widowmaker as only Sgt. Nathan Hale survives the skirmish.